Field of Invention
The present invention relates to a system of recycling exhaust heat from an internal combustion engine, and more particularly, to a system of recycling exhaust heat from an internal combustion engine including a recycling scheme circulating a working fluid using exhaust heat from the internal combustion engine.
Description of Related Art
An internal combustion engine is widely used in a vehicle, a ship, a small generator, and the like, and an attempt to increase efficiency of the internal combustion engine has been continuously conducted. The internal combustion engine generally discharges much heat as exhaust heat, and several systems collecting the exhaust heat to increase entire efficiency of the internal combustion engine have been developed.
When considering an apparatus and parts, an increase in load, and the like necessary to configure a system of collecting an exhaust heat, it is more efficient to mount a system of recycling exhaust heat in a large vehicle having large displacement and capable of carrying many people or cargo rather than a small vehicle having small displacement and which is light.
In a case of the vehicle, the system of recycling the exhaust heat includes a system using a turbo-compound and a system using a thermoelectric element.
The system using the turbo-compound is a scheme by attaching an exhaust turbine to an exhaust line and rotating the exhaust turbine by exhaust pressure to obtain an output, wherein this scheme may increase thermal efficiency of the entire system having the internal combustion engine installed therein, but may decrease the output of the engine itself due to the exhaust turbine acting as an exhaust resistance.
The system using the thermoelectric element uses a scheme of charging electric using the thermoelectric element generating electric using a temperature difference or assisting the engine by driving an auxiliary motor using the generated electric. However, since cost of the thermoelectric element itself is negligible and a space in which the thermoelectric element may be mounted is narrow, it is difficult to significantly increase thermal efficiency of the engine even though the thermoelectric element is actually mounted in a mass-produced vehicle.
In order to solve the above-mentioned problem and/or other problems, inventors of the present invention have developed a system of recycling exhaust heat circulating a working fluid using heat transferred from an exhaust side of the internal combustion engine and rotating the turbine using the working fluid. However, it is noted that the system of recycling the exhaust heat is not published to those without having the duty of confidentiality based on the point of time at which the present invention is filed.
It was expected that it is necessary to maximally increase an operating time of the turbine by circulating the working fluid as long as possible in order to increase efficiency of the system of recycling the exhaust heat and an experiment was performed accordingly. However, in the case in which the working fluid is circulated even when a temperature of the engine is low, it was found that fuel efficiency of the vehicle having the engine mounted therein is deteriorated. Therefore, a necessity of optimally setting a section in which the turbine is operated by circulating the working fluid has been increased.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.